The Story Behind The .io Top-Level Domain


Anyone who’s spent any time in the cryptosphere has probably noticed the number of crypto-related websites with the .io suffix. In fact, if you follow the tech sector and the start-up scene you’ve probably seen it too. So where did .io come from and what does it stand for?

Source: Pexels

The suffix to a web address is the Top-Level Domain or TLD. And the .io TLD is assigned to the British Indian Ocean Territory (BIOT), which incidentally has very little to do with cryptocurrencies or technology. The BIOT consists of a series of atolls halfway between Tanzania and Indonesia. The atolls are made up of over 1000 islands but cover less than 60 square kilometers in total. Diego Garcia is the largest island and is home to a joint US and UK military base.

So how did hundreds of tech start-ups, crypto related ICO websites and even Bitcoin casinos end up registered on the on the .io TLD? The domain has actually existed since 1997, and the first address registered on it was, owned by Levi Straus and Co. That was in 1998, but the association with technology came much later.

There is no specific reason that the BIOT domain became the domain of choice for tech startups, except that ‘IO’ is an abbreviation for the technical term input/output. However, it probably had more to do with the fact that by the mid-2000s, very few ‘.com’ addresses were still available.

Source: Pexels

Around that time, it also became fashionable for tech companies to build the domain into their company name, as in, or Opti.fy. This is known as domain hacking.

Today, the .io domain is the fourth most popular suffix amongst funded tech companies after .com, .co and .net. But that list includes companies that are much older. Amongst younger companies .io is probably almost as popular as .com.

One of the first high profile sites to use the .io TLD was www.agar,io, a multiplayer online action game. In the 2016 US Presidential primaries, Marco Rubio’s website was

The domain really took off in 2017 when initial coin offerings or ICOs became a thing. It has now become a rite of passage for blockchain projects to use the .io domain name on their token sale website.

One of the advantages of using a .io address is that Google classifies the domain as a gccTLD or Generic Country Code Top Level Domain. That means it isn’t indexed as a country-specific website. Country-specific websites with domains like .ca or .fr are sometimes excluded from searches in country-specific searches.

Source: Pexels

Not everyone agrees that the .io TLD is the way to go. Some people feel they signal to the world that your company can’t afford to buy the .com domain. They may also prove to be a fad – popular today, but dated tomorrow.

If a company’s critical success factor is the last few letters of its web address, it probably needs to rethink its business model. But, if blockchain projects continue to flourish, we may find ourselves typing .io into our browsers a lot more often.